The invention describes a method for monitoring a fuel injection system in which a body sound signal is detected and used for evaluating the fuel injection system.
In DE 195 48 279 A1 a method and an apparatus are disclosed for monitoring a fuel metering system in which a fault in the metering system is recognized whenever a signal put out by a body sound sensor differs from a set value. The amplitude or the duration of the signal put out by the body sound sensor is compared with a reference signal and, if there is a difference, a defective injection valve is recognized. This method, however, is relatively inaccurate.
The problem to which the invention is addressed is to offer a more accurate method for monitoring a fuel injection system by evaluating the body sound signal.
The stated problem is solved by the features of the independent claims. An important advantage of the invention is that the body sound signal is integrated across a window of measurement, and that the integrated body sound signal is used as a measure of the functionality of the fuel injection system.
Advantageous embodiments and improvements of the invention are given in the dependent claims. The body sound signal is preferably filtered with a given band of frequencies between 1 Hz and 10 kHz. Thus a signal is produced which permits a precise conclusion as to the functionality of the fuel injection system.
The fuel injection system of an internal combustion engine must be monitored for correct operation, especially in the case of high injection pressure.
The fuel injection system of an internal combustion engine must be monitored for correct operation, especially in the case of high injection pressure.